Call center or support workers often need to walk customers through complex multi-step procedures, for example, in diagnosing or solving problems such as fixing PC networking problems, diagnosing and fixing problems in machinery, solving mobile phone problems for customers, and others. Challenges in following through such procedures may include cognitive overload in keeping track of the current state of the conversation, e.g., where exactly am I in the procedure? How did I get here? A further complication is that multiple lines of inquiry may be active simultaneously. Conversation can span multiple calls, and resuming a conversation can be tedious.